Ivesia sericoleuca
Ivesia rhypara
Plumas ivesia, Plumas mousetail
grimy ivesia, grimy mousetail
decumbent to ascending, 1.5–4.5 dm.
± prostrate, (0.1–)0.2–1.5(–2) dm.
10–20(–30) cm; sheathing base densely strigose abaxially;
stipules absent;
petiole 2–6(–10) cm, hairs abundant, usually spreading, 1–4 mm;
leaflets 20–35 per side, loosely overlapping, 3–15 mm, lobes 0–4, oblanceolate to elliptic, hairs abundant, spreading to ascending, (0.5–)1–3(–4) mm.
tightly cylindric, 2–10 cm; sheathing base densely hairy abaxially;
petiole 0.5–4(–10) cm;
lateral leaflets 4–10(–15) per side, overlapping at least distally, ± flabellate, 0.5–3(–4) mm, incised to base or nearly so into (0–)2–4(–9) elliptic to obovate or orbiculate lobes, apex usually not setose, surfaces densely hirsute, cryptically glandular;
terminal leaflets indistinct.
3–8(–10).
(0–)1;
blade vestigial.
20–120-flowered, (2–)4–14 cm diam., flowers mostly arranged in several to many tight glomerules of 5–10 flowers.
5–60(–100)-flowered, congested, 0.5–5(–7) cm diam.
1–3(–12) mm.
1.5–4(–8) mm.
10–15 mm diam.;
epicalyx bractlets narrowly lanceolate to narrowly elliptic, (1.5–)2–2.5(–3) mm;
hypanthium campanulate to shallowly turbinate, 1.5–3 × 2.5–4.5(–5) mm, often nearly as deep as wide;
sepals sometimes purple-suffused, 3–5.5 mm, acute to acuminate;
petals white, broadly spatulate to broadly obovate or obcordate, 4–7 mm;
stamens 20, filaments filiform, 1.5–3 mm, anthers white to cream, 0.5–0.7 mm;
carpels 2–7, styles 2.5–4 mm.
4–8 mm diam.;
epicalyx bractlets 5, linear to elliptic or narrowly ovate, 0.8–1.6(–2.1) mm;
hypanthium patelliform to shallowly cupulate, 1–1.5 × (1.5–)2–3(–3.5) mm;
sepals 1.4–2.5(–2.8) mm, acute;
petals white to pale yellowish, linear to narrowly oblanceolate, 1–1.5 mm;
stamens 5, filaments 0.6–1.8 mm, anthers maroon or yellow with maroon margins, oblong, 0.3–0.6 mm;
carpels 1–2(–4), styles 1–1.5 mm.
brown, 2–3 mm.
brown, 1.2–1.6(–2) mm, smooth, prominently carunculate.
= 28.
Ivesia sericoleuca
Ivesia rhypara
Of conservation concern.
Ivesia sericoleuca is known from valleys and flats in the northern Sierra Nevada. Many historic collections were identified and distributed as I. unguiculata, and circumscriptions prior to 1962 include I. aperta (hence reports from Nevada).
Hairs are usually dense in plants of Ivesia sericoleuca, such that the leaves, and occasionally the stems and branches, are silvery gray, especially in Sierra Valley and the Feather River drainage. Plants in the Truckee River drainage tend to be less hairy with redder stems, less glomerate inflorescences, shallower hypanthia, and more conspicuous glandularity.
As mentioned by J. T. Howell (1962), the chromosome count given for Ivesia sericoleuca by P. A. Munz (1959) most likely was based on a collection of I. aperta var. aperta. The chromosome count given here is instead based on Kruckeberg 3665, originally distributed as I. pickeringii.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 2 (2 in the flora).
Ivesia rhypara forms densely hairy mats or mounds on isolated edaphic sites in the northern Great Basin. Only one of the widely disjunct population clusters is recognized as a distinct variety; the others have general differences in gestalt, but no significant distinctions have been determined (B. Ertter 1989). Isozyme analysis likewise does not show significant differences (T. Kaye et al., unpubl., BLM and Oregon Dept. of Agriculture, 1991). Reproductive studies by D. Wiens (pers. comm.) show low seed set (ca. 5% in var. rhypara, somewhat higher in var. shellyi), possibly indicating a deleterious genetic load.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Plants (4–)8–30 cm diam.; inflorescences (1–)2–5(–7) cm diam.; scarcely or cryptically petrophytic in bedrock overlain by rubble and soil. | var. rhypara |
1. Plants 2–10(–15) cm diam.; inflorescences 0.5–2(–5) cm diam.; overtly petrophytic in boulders and outcrops. | var. shellyi |
CA
WildflowerSearch
iNaturalist
USDA Plants Database
OR
Flora NW
PNW Herbaria
